1. ESS Plans and Synergies with CERN
K. Bongardt IKP
FZ Jülich, Germany

2. ESS plans and synergies with CERN
• ESS Update Report, Dec 2003
- Full ESS facility: 5 MW SP & 5 MW LP Hg targets with 2 compressor
rings & 114 mA, GeV H- linac
- Scientific relevance of SP & LP target
- 15 MW LP Target: Scientific relevance & 3 GeV H+ linac
• ESS-I and the 5 MW LP ESS
- ESS-I
- 5 MW LP ESS, upgradeable: Accelerator, target options,
1 MW PbBi MEGAPIE target, scientific relevance and instruments
• Current situation
- ESFRI and UK
- Sites
- FP7 preparatory study
• Synergies with CERN

3. ESS Update Report, Dec 2003
• ‘The European Spallation Source (ESS) project, as defined
by the four volumes ESS Report 2002, was presented to
the public, the general neutron user community and
European decision makers at a meeting in the former house
of parliament in Bonn, May 2002.
• In January 2003 it became clear, that a decision to built
ESS would not be likely forthcaming by the end of early
2004. The ESS council therefore decided to wind down all
technical & project planning activities and limit the ESS
efforts to documenting the technical and planning status.
• The ESS Update Report, Dec 2003, is a summary of the
amount of work, technical definition & progress achieved
during the period from May 2002 to early 2003.‘

4. ESS Update Report, Dec 2003 New items, compared to
ESS Project Report 2002,
Vol 1-4 are mainly in:
- Chapter 1:
SC Reference linac
- Chapter 5:
Instruments & scientific use
- Chapter 8:
Safety & licensing
ESS Update Report 2003:

5. Full ESS Facility: 5 MW SP & 5 MW LP target
Size of
850 m x
1150 m
ESS facility consists of a 10 MW, H- accelerator capable of delivering
5 MW, 1.4 s pulses to a short pulse (SP) target at 50 Hz & 5 MW,
2 ms pulses to a long pulse (LP) target at 16 2/3 Hz. Both targets have
22 beamlines & liquid Hg is choosen as material.

6. Two stacked 1.334 GeV accumulator rings
Main parameters:
- Mean radius 35m
H- stripping foil inside
low field dipol
Protons/ring 2.34 x 1014
Bunch, pulse at target
0.6 s, 1.4 s
• Chopping the incaming beam at 2.5 MeV helps minimizing the ring
beam losses and reduces radiation damage.
Transverse & longitudinal profiles of injected H- beam are cleaned by
stripping foils in large 180 ° achromatic bending section.

7. ESS SC Reference Linac: 114 mA H- beam, 1.334 GeV
• Short description: 2 x 65 mA H- beams are combined together at 20 MeV
in a funnel section. High frequency Superconducting (SC) cavities
accelerate the beam from 400 MeV on. Moderate gradient of 10 MV/m
in SC linac is used to keep RF power couplers within reasonable limits.
After reducing energy spread by bunch rotation (BR) to  2 MeV, halo
scraping in large 180 ° achromatic section.

8. ESS SC Reference Linac: Double pulse & chopping
Compressor rings get
2 x 0.5 ms long pulses,
70 % chopping
LP target get 2 ms pulse,
no chopping, but 50 %
more power in SC
3.5 m chopper line:
- 2 deflecting sections
to absorb < 5 kW
- 2 ns rise,100 us flattop - 5 combined focusing
elements
Little filamentation in
20 MeV ESS front end

9. ESS SC Reference Linac: 1120 MHz SC high ß linac
• Main parameters of 308 m long 1120 MHz SC linac
- 43 cyromodules, each housing 4 elliptical bulk Nb cavities, 6 cells at
ß = 0.8, equipped with one SC main coupler
- As overall ESS RF d.c. is about 11 %, we limited ourself to only 0.85
MW peak power for unchopped LP pulse
- Only 10 MV/m accelerating gradient at Q0 = 1010 is assumed: Peak
magnetic field well blow 50 mT & large  2 kHz 3 db bandwidth for
unchopped 114 mA beam

10. ESS SC Reference Linac: Particle tracking in SC linac
Phase slip along SC linac:
Bunch centre is always between
 90 °, energy gain in every cell.
Results are stable synchrotron
Oscillation & small filamentation,
obtained by 3 d tracking with
228 mA bunch. After BR, energy
spread <  1 MeV.
RF amplitude & phase errors:
Field errors along the ESS linac
will lead to shift of bunch in energy and time/phase, maybe causing
large energy shift after BR.
Assuming  1 % ,  1° RF errors
in each SC cavity, energy shift
<  1 MeV.
Input, large deviations
& linac end
Before & after BR: Lines are  1 MeV

11. Scientific relevance of 5 MW SP & LP targets
A neutron working group under ESFRI (European Strategy Forum for
Research Infrastructure) published a report in early 2003, comparing scientific importance of ESS high priority instruments, compared to SNS 1.4 MW SP source.
Not visible are low
power targets like ISIS 2.TS & proposed
SNS LW one. But they
are comparable for
dedicated applications.
• 5 MW SP source is 3 x better than 1.4 MW SNS for all cases.
For same instruments, 5 MW LP source is also better than SNS,
even better compared to 5 MW SP source.

12. 15 MW LP Source: Scientific relevance & 3 GeV H+ linac
• Stimulated by the ESFRI 2003 findings, beginning 2003 discussions started about the
scienific releavance of 15 MW LP source. In 1. order, relative performance is increased
by factor 3, leading to at least same gain factors as full ESS. Open questions by end 2003:
Validity of 1. Order scaling & target design.
• In response to these discussions, 3 GeV,15 MW H+ linac is shown in ESS Update Report
2003, based on SC Reference linac.
No chopper line & no achromatic bending section. Only 4 % RF d.c.
1 GeV, 5 MW H+ linac requires only 28 SC cyromodules, 201 m in length.

13. ESS situation 2007, ESS initiative (ESS-I)
Several of following transparencies are based on presentation P. Tindemans, chair of ESS-I,
at ICANS XVIII, Dongguan, April 2007
• Purpose: Keep ESS on the political tables, and demonstrate
to the (young) scientists that the fight to get ESS goes on.
• Members:
- European Neutron Scattering Association (ENSA)
- Consortia for site candidatures: Yorkshire, Scandinavia, Hungary,
Spain/Basque Country, Sachsen/Sachsen-Anhalt
- Some labs: ILL, FZ Jülich (after discussing with all German labs)
- Independent chair
ILL is host
• Looks like we are succeeding!

14. The ESS 2007 to be built Arguments
• SNS + 10 (+) years  ESS ‘5 x SNS’ in many areas
• Maintain network of sources
• Cost-effectiveness dictates: Eventually as many instruments as possible
• Start in as complementary a mode as possible
Choice
• Start with 5 MW LP target, 20 instruments:
- As many ancillary and science facilities as affordable
- Ready to operate in ‘industry-mode’ too: Access mode (financial, time), IP
arrangements, demonstration experiments, standardised procedures, etc.)
and as much as possible upgradeable to:
- More power
- More target stations (SP, LP, low power TS for dedicated applications)
- More instruments
Costs
>1.2 B€2006 investment, depending on upgrade possibilities;
100 M€2006/y operating

15. ESS 2007, 5 MW LP target
• Preference is still liquid Hg target, but an alternative solid rotating
target was already part of the ESS design study.
• Options compared, including first experience of liquid Hg SNS target,
at workshop in Lund in March Technically and in terms of
performance no dramatic difference. So if Hg raises political problems
(though e.g. Swedish government does not see problem to license a
liquid Hg target) other options exist.
• Liquid Pb/X eutectic suggested as target material to avoid production
of long-lived actinides. Consequences like higher melting temperatures
must be studied.
Thermal - hydraulic effects of LP target with 15 MW & 900 kJ/ pulse,
e.g. beam window
• Specified must be secure storage of very high activated liquid target material and transport to solidification plant.

16. ESS 2007, 1 MW PbBi MEGAPIE target at PSI
Last fall, PbBi liquid metal MEGAPIE target was succesfull commissioned at PSI, reaching about 1600 MWh until planned shutdown in Dec Typical beam power was about 700 kW.
Phase 3 of beam commissioning:
The third and final phase of the start-up procedure was successfully accomplished on the 17th of August, where the power was stepwise increased to full power 700 kW (1200 A proton current). After some 10 minutes time with stable proton beam at each step, the beam was interrupted to follow the temperature transients in the target. All systems operated very stable at all power levels.
Startup & operation of CW target is much easier than for SP one.

17. ESS 2007, Scientific relevance of 5 MW LP target
ESS-I Rencurel workshop, Sep 2006, agreed on better LP performance
Important Contribution to European Priority Research Mission
Flagship Field of Research
Full ESS,
5 MW SP & LP
5 MW LP
Functional Materials, Microsystems and IT, Nanotechnology
Solid State Physics WL SL
Microsystems and IT, Functional Materials, Nanotechnologies, Traffic & Transport, Sustainable Development
Material Science &
Engineering
Functional Materials, Nanotechnologies, Traffic & Transport, Sustainable Development
Liquids & Glasses
Soft Condensed Matter
Functional Material, Health, Sustainable Development
Chemical Structure
Kinetics & Dynamics
Health and Biotechnology
Biology & Biotechnology
Traffic and Transport, Cultural Heritage, Sustainable Development
Mineral & Earth Science, Environment and Cultural Heritage
Cosmology, Origin of the Universe, Education, Public Understanding
Fundamental Physics

18. ESS 2007, Changes in European Political Landsscape
1. ESFRI Road Map 2006 (modeled after DoE 20-year
facilities outlook) + strong desire of European
Commission to implement this. ESS is high on this 35-
project list – across all fields of science – as one very
mature projects.
2. UK Neutron Review March 2006: UK should participate in
European next generation project. Decision on feasibility
study into 1 MW upgrade of ISIS postponed until
European efforts fail.
3. Several very serious site candidates backed by national
governments with money; see next slide.

19. ESS 2007, Serious site candidates
Scandinavia/Sweden: Lund
• Sweden formally proposed March 2007 to host ESS, made a 300 M€ offer
• Swedish government appointed negotiation team led by former finance minister Alan
Larson to tour Europe
• Government established ESS project unit at Lund university under Colin Carlile (now
professor at Lund University), with budget of several M€ until end 2008
• 22/23 October 2007, Round Table with interested governments and EU
Spain/Basque Country: Bilbao
• Formal proposal by national government and Basque government: 50-50; M€
available and 20 M€ for preparations
• When presidents and prime ministers meet… Chirac and Zapatero: ‘French support
for Bilbao; joint WG to investigate things’
• Bilbao team under Juan Urrutia tours Europe too
• About to appoint international director for ESS-Bilbao
Hungary
• Formal bid May 2007: Site either near Budapest or in Debrecen
• Ministry for Economy and Transport in charge
• Structural Funds EU, European Investment Bank
• Strong regional support
• Equally making the Europe tour
UK: Culham science park (including RAL), Yorkshire ?

20. ESS 2007, FP7 proposal granted (5 M€ EU support)
(EU FP7 funds ‚preparatory‘ studies for ESFRI Road Map projects)
• Adressing more in-depth safety issues, socio-economic aspects,
regulatory requirements
• Environmental compliance issues different target materials
• Radio-active inventory, emission, handling, storage
• Decommissioning
• Upgradeability
• Novel ideas for user operations, and for governance
• Enhancing support for ESS: Industry, funding agencies, public at large,
politics
Overall report 24 months, but specific reports much earlier, and 6- and 12-months intermediary reports to serve governments’ decision making.

21. ESS 2007, Synergies with CERN SPL linac
• Both high currents ESS linacs, either 114 mA H- one or
150 mA H+ one uses pulsed high ß SC cyromodules from
400 MeV. Timely construction of choosen ESS linac
requires complete cyromodule as full power test-bed of
pulsed SC cavities. Common interest with pulsed CERN
SPL linac is evident .
• Depending on choosen ESS upgrade scenario, also low
energy chopping line is required, maybe even for 150 mA
H+ linac. If a dedicated low power target station, like ISIS
2. target or planned SNS LW target, becames of interest
for ESS upgrade, then beam intensity of 1 ms pulse can
by 50 % reduced in low energy chopping line.
Common interest with pulsed CERN SPL linac is evident .

22. Summary • Summarized is full ESS facility with 5 MW SP & LP target, as
documented in the ESS Update Report Emphasis is given to
the choosen ESS SC Reference Linac with its low frequency front
end, followed by high frequency SC cyromodules. Both pulsed ESS
linacs, either 114 mA H- or 150 mA H+, use SC cavities > 400 MeV.
• After ending ESS project by end of 2003, ESS-I group succesfully
promoted ESS to be in the highest category of maturity of the
European Road Map. Consensus on ESS facility is to start with
5 MW LP target, about 20 instruments, being upgradeable laterly.
• Recently formed FP7 study group will look at accelerator & target
problems, associated with various upgrade scenarios.
• Complete cyromodule as full power test-bed of pulsed SC cavities is
on common interest for ESS & CERN SPL linacs. Low energy
chopping line could also be of interest, depending on ESS upgrade.